Across the Multiverse
by Angel-son of Caesar
Summary: In which characters travel across the multiverse to interact uniquely with other characters in other universes. READ EXPLANATION CHAPTER FIRST. JamesLily, rated T because that's how all my stories are.
1. Explanation

**Across the Multiverse**

**WARNING: **The following is an excerpt from the story Timeline by the late Michael Crichton (God bless him). Here is a citation in MLA format. Please don't sue. **YOU MUST READ THIS.** It explains the way this story works.

Crichton, Michael. Timeline. New York: Ballantine Books, 1999. Print.

**Disclaimer: DEFINITELY not mine.**

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Page 123-4:

"You mean time travel," Marek said.

"No," Gordon said. "I don't mean time travel at all. Time travel is impossible. Everyone knows that."

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"The very concept of time travel makes no sense, since time doesn't flow. The fact that we think time passes is just and accident of our nervous systems-of the way things look to us. In reality, time doesn't pass; we pass. Time itself is invariant. It just _is_. Therefore, past and future aren't separate locations, the way New York and Paris are separate locations. And since the past isn't a location, you can't travel to it."

They were silent. They just stared at him.

"It is important to be clear about this," Gordon said. "The ITC technology has nothing to do with time travel, at least not directly. What we have developed is a form of space travel. To be precise, we use quantum technology to manipulate and orthogonal multiverse coordinate change."

They looked at him blankly.

"It means," Gordon said, "that we travel to another place in the multiverse."

"And what's the multiverse?" Kate said.

**AN: Okay, then Gordon goes on to discuss the multiverse and quantum physics and stuff you people don't really care about (if you do, read the book!). To sum things up, physicists used to think stuff traveled in waves (light waves, radio waves, etc.), but then later found out that everything was actually made up of particles, which they called quanta, and "quantum theory" describes how these "quanta" behave. But quantum theory is just a set of mathematical equations, and the physicists couldn't visualize the world expressed by those equations, but quantum theory was proven over and over again, so they couldn't very well gainsay it. Now we go back to Timeline for more explanation.**

Page 126-7:

Many physicists tried to explain the equations, Gordon said. Each explanation failed for one reason or another. Then in 1957, a physicist named Hugh Everett proposed a daring new explanation. Everett claimed that our universe-the universe we see, the universe of rocks and trees and people and galaxies out in space-was just one of an infinite number of universes, existing side by side.

Each of these universes was constantly splitting, so there was a universe where Hitler lost the war, and another where he won; a universe where Kennedy died, and another where he lived. And also a world where you brushed your teeth in the morning, and one where you didn't. And so forth, on and on. An infinity of worlds.

Everett called this the "many worlds" interpretation of quantum mechanics. His explanation was consistent with the quantum equations, but physicists found it very hard to accept. They didn't like the idea of all these worlds constantly splitting all the time. They found it unbelievable that reality could take this form.

"Most physicists still refuse to accept it," Gordon said. "Even though no one has ever shown it is wrong."

Everett himself had no patience with his colleagues' objections. He insisted the theory was true, whether you liked it or not. If you disbelieved his theory, you were just being stodgy and old-fashined, exactly like the scientists who disbelieved the Copernican theory that placed the sun at the center of the solar system-and which had also seemed unbelievable at the time. "Because Everett claimed the many worlds concept was _actually true_. There really _were_ multiple universes. And they were running right alongside our own. All these multiple universes were eventually referred to as a 'multiverse.'"

"Wait a minute," Chris said. "Are you telling us this is true?"

"Yes," Gordon said. "It's true."

"How do you know?" Marek said.

"I'll show you," Gordon said.

**And then Gordon proves that it is true. Now that you know more about quantum physics than you wanted to, let's move on to exactly _how_ to move through the multiverse. Gordon goes on to explain that they create wormholes through quantum foam to travel to different universes. Then Stern explains quantum foam. Basically, when the big bang happened, there were some imperfections in the universe, and, in Stern's words:**

Page 136:

"...And the imperfections never got ironed out. They're still a part of the universe."

"They are? Where?"

"At subatomic dimensions. Quantum foam is just a way of saying that at very small dimensions, space-time has ripples and bubbles. But the foam is smaller than an individual atomic particle. There may or may not be wormholes in that foam."

"There are," Gordon said.

"But how could you use them for travel? You can't put a person through a hole that small. You can't put _anything_ through it."

"Correct," Gordon said. "You also can't put a piece of paper through a telephone line. But you can send a fax."

Stern frowned. "That's entirely different."

"Why?" Gordon said. "You can transmit anything, as long as you have a way to compress and encode it."

**Gordon goes on to explain that all you'd need to do this to a human was a really powerful computer. By the way, compressing and encoding basically means saving the instructions for how to recreate something, instead of just saving a thing. So instead of saving a picture of a red square on a white background, with millions of pixels and millions of information, the computer just says make so many pixels white, then so many red, and so on, cutting the data to a very small amount. Then Gordon demonstrates multiverse travel. This is shocking news to the other characters.**

Page 157:

"But this, uh, method of shrinking a person, it requires you to break her down-"

"No. We destroy her," Gordon said bluntly. "You have to destroy the original, so that it can be reconstructed at the other end. You can't have one without the other."

"So she actually died?"

"I wouldn't say that, no. You see-"

"But if you destroy the person at one end," Kate said, "don't they die?"

Gordon sighed. "It's difficult to think of this in traditional terms," he said. "Since you're instantaneously reconstructed _at the very moment_ you are destroyed, how can you be said to have died? You haven't died. You've just moved somewhere else."

**And one more thing to think about...**

Page 179-80:

"It may be easier to understand," Gordon said, "by seeing it from the point of view of the other universe. That universe sees a person suddenly arrive. A person from another universe."

"Yes..."

"And that's what happened. The person _has_ come from another universe. Just not ours."

"Say again?"

"The person didn't come from our universe," Gordon said.

Stern blinked. "Then where?"

"They came from a universe that is almost identical to ours-identical in every respect-except that they know how to reconstitute it at the other end."

"You're joking."

"No."

"The Kate who lands there isn't the Kate who left here? She's a Kate from another universe?"

"Yes."

"So she's almost Kate? Sort of Kate? Semi-Kate?"

"No. She's Kate. As far as we have been able to tell with our testing, she is absolutely identical to our Kate. Because our universe and their universe are almost identical."

"But she's still not the Kate who left here."

"How could she be? She's been destroyed, and reconstructed."

"Do you feel any different when this happens?" Stern said.

"Only for a second or two," Gordon said.

**So you see, my friends, that quantum theory is troublesome. But the idea here is that YOU CAN TRAVEL BETWEEN UNIVERSES and, essentially, through time. Which is, of course, what our characters are going to do. Hope you understand this and happy reading!**


	2. James' Twin

**Across the Multiverse**

#1: James' Twin

Summary: Lily and James are walking through the halls when a man around their age approaches them and, when asked about his identity, claims to be James' brother.

**AN: Thought I'd start off with something simple. Been wanting to do this for a while.**

**Disclaimer: Not mine.**

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It was a bright and sunny day at Hogwarts as James Potter merrily made his way through the old castle's halls.

Actually, it was dark and cloudy out, rather dreary-looking overall, and it was nighttime, but, to James, it was a bright and sunny day.

This was because he was about to go walk and talk with the love of his life, Miss Lily Evans.

Upon finding the aforementioned girl, he was greeted cordially and an inquiry was made about his actions as of late.

"Potter," Lily said, not looking at him. "What are you doing here?"

"Why, my dear Miss Evans," James replied, "I do believe you promised to take a stroll around the halls with me!"

"I never did any such thing," Lily retorted. "You're being silly. Why would I like to take a stroll around the halls at this late hour? And with you, nonetheless!"

"We have patrols, Lily dear," James countered, dropping the act.

Lily froze for a second, then cursed under her breath. "Alright, give me a few minutes to get ready."

James looked at her and frowned. "Why? You look fine."

Lily examined her school robes, dirty from the day's work. "What, in these? No way."

James rolled his eyes amusedly. "We're just patrolling, Lily. It doesn't matter what you wear. No one will see you anyway."

"Well, I don't care. I want to look good," Lily said stubbornly, as she made her way to her bedroom.

James laughed. "Freshening up for me, are you?"

Lily stopped dead in her tracks and turned around. "Not at all. Let's go."

James was rather taken aback by this sudden gear-change. "Err...okay."

They left the room and began to patrol the halls.

After about ten minutes, Lily realized that she and James were actually making civil, pleasant conversation and getting along well.

In fact, she was rather enjoying herself.

James Potter, on the other hand, was ecstatic.

The two Heads continued patrolling the halls, and were almost finished when it happened.

It happened while James was in the middle of a funny story (which he would very much liked to have finished). He and Lily were laughing so hard it was difficult for him to continue telling the story.

"But, then, just when we're about to get Peter out of the enlarged (but rapidly shrinking) cauldron," James continued through his laughter, as Lily wiped her eyes, "Sirius comes running up to us, slips on the potion, and knocks Remus into Peter, throwing them both into the cauldron! So, _then_, we have to go-"

Suddenly, they saw bright flashes coming from a room just up ahead.

They froze.

James turned to face Lily. "Should we go look?" she asked.

James thought for a moment, then nodded. "I'll go first."

They crept towards the room. When they got to the door, James stopped and motioned to Lily to keep quiet and stay outside. She nodded and they both drew their wands.

"Be careful," she whispered. He almost laughed out loud.

Slowly, he slipped into the room. Lily held her breath, her heart was pounding, and she was ready to run, scream, or jinx something.

A couple of seconds later, she heard James' voice. "Lily! I think it's okay!"

She released her breath and walked inside, wand still raised.

James was helping someone up. And as the man turned to face her, Lily gasped.

He was identical to James.

The hair, the mouth, the nose, the hands, the eyes-wait.

The eyes weren't the same.

While James' eyes were a brownish color, the other man's eyes were a startling green.

Now that she looked closer, she realized he wasn't at all identical to James; his posture and build were different, it was just the face that looked similar.

She realized by the man's questioning look that she was still staring openly at him.

She cleared her throat embarrassedly, causing James to start (for he, too, was staring at the man with a curious expression on his face).

"Excuse me, but...who _are_ you?" she asked the man.

He smiled.

"My name is Harry Potter."

That explained the similar face, then, she thought.

"Potter?" James said. "A relative of mine, perhaps?"

"I take it you are James Potter?" the man returned.

"That is correct," James replied.

"Then, yes, I am. A very close relative, in fact."

"Really? So how are we-" James' next question was cut off as Harry gestured towards Lily.

"And who is she?"

"Her?" Harry nodded. "She's...er...she's Lily Evans, the love of my life."

"Cut it out, Potter," Lily snapped.

Harry's eyes widened.

"Oh, I'm sorry, are you two not together?"

"Of course not!" Lily cried, as James muttered, "I wish..."

Harry cursed mentally.

"Wait a moment," James said, remembering his earlier question. "How _are_ we related, Harry?"

Harry panicked.

"Err...well...I...erm...we're kinda...sorta...well, you see...I'm your...I'm your...I'm your..."

"Yes?" James prodded.

A thought flashed through Harry's brain, and he blurted it without thinking.

"I'm your long-lost twin brother."

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Lily and James stared.

"His...brother? You're his brother?"

"That's right, his twin brother."

James looked suspicious for a moment, but then smiled widely and said, "Well, it's nice to meet you, then, Harry! We should go back to Gryffindor Tower. You can stay with my friends."

"But, don't we have to finish patrols?" Lily protested.

"Do we?" returned James.

Lily sighed. "I guess not. We're almost done anyway."

"Perfect," said James. "Let's go."

He led the way back to Gryffindor Tower.

The three teenagers entered the common room together.

"Good night, Lily!" said James cheerfully.

"Err...good night, Potter," Lily said. The two of them were so confused that they forgot that they weren't actually supposed to sleep in Gryffindor Tower anymore.

"Now, Harry, if you'll just follow me," said James.

"Yes, of course. Lead the way."

James and Harry went to the Marauders' dorm.

Upon opening the door, James was met with a chorus of various greetings. Then Harry walked in, and they all fell silent.

Then Sirius asked, "Who's he?"

"He's Harry Potter."

Remus blinked. "Potter? A relative?"

"Yes, apparently, I have a twin."

Peter gaped. "A twin? You have a twin brother?"

"Shocking, I know," began Harry, stepping forward and away from the door, which James surreptitiously shut, "but, you see-"

"SIRIUS, NOW!" yelled James.

Sirius and Remus sprang up and grabbed Harry as Peter conjured up a small chair. Harry struggled with the two others for a bit, before being taken down and shoved into the chair. James flicked his wand to restrain Harry with ropes.

"What are you doing?" he argued, fighting fruitlessly against his bonds. Peter made sure to hold him down. "Let me go! Why are you doing this?"

"Stop talking," James commanded, and Harry fell silent. "Now, who are you?"

"I told you," Harry said, frustrated, "my name is Harry Potter!"

Remus studied their captive. "He's telling the truth," he said finally.

"Fine," continued James. "But how are you _really_ related to me? I know you're no brother of mine. No one in my family has eyes like that."

"Your wife does," Harry muttered, ceasing his struggle and looking at the ground.

"What was that?" James said quickly.

"I said, your wife does," Harry reiterated.

"How do you know this?"

"Well, you see...this is rather difficult to say."

"Just say it," Sirius snapped.

"I'm from the future. Or, rather, I'm from a different universe, which is in the future."

The Marauders were silent for a few seconds.

"Who _are_ you?" James asked quietly, in an awed voice.

Harry looked him in the eye.

"I, Harry James Potter, am your son."

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James' jaw dropped.

Remus stared.

Peter's eyes widened.

Sirius said, "Lies."

Harry looked at Sirius. "You, Pads, are my godfather."

"Never mind, then," said Sirius, who removed the bonds and embraced Harry.

"Wait, but, if you're from another universe, how did you get here? And why did you come?" asked James, still shocked.

"Sirius and Remus told me, many times, about how you and Mum actually got together, so I figured-"

"That you had to come here and make it happen?" Remus finished.

Harry grinned. "Of course. Plus, I figured it would be a _great _time to meet and get to know you guys-"

"Wait. What was that? Meet and get to know us?" Sirius interrupted. "Why would you need to do that?"

Harry realized his mistake. "Erm...you didn't let me finish. I was going to say meet and get to know you guys...while we're all the same age," he invented wildly.

"Oh," said Peter. "I see. Good plan."

"Yes, well, Sirius and Remus always told me that a man claiming to be James' twin showed up randomly in their seventh year-"

"That's you," said James.

"-and then went to Lily and somehow convinced her to go out with James. Then the rest was history."

"Wow, we're rather boring storytellers, aren't we?" commented Sirius.

"Well, of course, you made it sound better, but that's the gist of it," replied Harry.

"Oh, so you're the bad storyteller, then. That's much better," said Remus.

"Alright, enough with the jokes," said James. "My son needs to go convince my wife to go out with me so he can be conceived after Lily and I make hot love-"

"Dad!" Harry cried, covering his ears.

The Marauders all laughed.

"Okay, but seriously, enough with traumatizing jokes. Harry, go work your magic!"

Harry sighed. "See, Dad, the thing is, I never told anyone what I said to Lily. So Sirius and Remus don't know, so they couldn't tell me. So I don't know what to do. All they said was that the morning after he arrived, Saturday morning, he just went and talked to Lily."

"Then I guess all we can do is sleep and wait."

"I guess so."

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The next morning, Harry and James got many stares on their way to breakfast.

After eating, the Marauders left to go play some Quidditch, and Harry went to find Lily.

Seeing her in the library, he cautiously approached. "Err...Lily?"

Her eyes flicked up to his face momentarily before going back to her homework. "What do you want, Potter? Is this another date proposal?" she snapped.

"Merlin, no."

She looked up, startled, and saw, in what she thought to be James Potter's face, her own eyes looking at her timidly. "Oh, I'm so sorry, I thought you were your brother!"

Harry gave a nervous laugh. "Yes, about that...you see, James isn't really my brother."

Lily's eyes narrowed. "What do you mean?"

"Well...to begin with, do you believe in time travel?"

"As in, the use of Time-Turners? I know they work."

"No, I mean real time travel, over longer periods of time."

"Well...with magic, anything's possible, I suppose."

"Yes, anything is. But do you believe that one can travel through time, specifically?"

Lily was eyeing him quizzically. "I guess so..."

"Well, you're wrong. Time is not a destination, so you can't. But you can do the equivalent of it, by traveling through universes to a universe that's in the past."

"Oh!" Lily brightened immediately. "You're talking about Everett's multiverse theory!"

"Precisely!" said Harry, relieved and immensely happy that she'd caught on. "Well, you see, Hugh Everett was right. And, as a result...I'm from a universe in the future."

Lily was ecstatic. "Really? That's amazing! But, wait. What does this have to do with Potter? I mean the other Potter. James."

Harry got uncomfortable again. "Well, I wasn't lying about my name and the fact that we're relatives. But we're not brothers. And my full name is actually Harry James Potter."

Lily laughed. "So you're named after him?"

"Yes. James...James is my father."

Lily's eyebrows shot up. "Oh, is he, now?"

"Yes, he is."

"Well, that's, erm...wonderful, I guess. What's your mother like?"

"Well, Sirius and Remus tell me that she was very beautiful and extremely intelligent. They said that James was so very much in love with her. Apparently, it got very annoying, always hearing about how perfect she was or the way her hair shone in the light or the beauty of her laugh." Harry chuckled at this.

Lily was not looking happy at all. "Indeed. So she was perfect, then?"

"The Marauders liked to think so. And, oh, I just remembered! James always used to go on about her eyes, it got on their nerves so much. It was his favorite thing about her. So, when she gave birth to me and he found that I had her eyes, he was just so happy." Harry smiled at the thought.

"Oh, really?" Lily was barely feigning interest anymore. "So you have her eyes? That means her eyes would be, let's see, emerald green and almond shaped?" She gave a little laugh. "You know, that sounds awfully like my eyes..." The aforementioned eyes widened and Harry smiled even wider.

"Are you saying that...am I...really?"

Harry nodded, beaming at her.

"Oh, Merlin...oh, Merlin." Lily was completely blown away. "Oh my Merlin...I marry James Potter and _give birth to his son_. Sweet Mother of Merlin..."

Harry laughed. "I hope, now that you know this, that you will go out with him this weekend?"

She looked back up at Harry and smiled. "I suppose I must, don't I?"

"Well..." Harry pretended to think, "You don't really have to. But if you don't, Voldemort might win the war. I kill him, you know."

Lily laughed, but then got serious. "Don't go around saying such ridiculous things, young man, or you might end up dead."

"Yes, Mum," he replied. "But, really, I do. Anyway, isn't there something you'd like to go tell my father now?"

"Oh, yes, of course, I almost forgot."

"Good. Well, I guess this is good-bye, Mum." Harry grew very sad at the thought.

"Yes, well, I'll see you in a few years, won't I?" Lily laughed.

"Yes...but, you see...never mind. You will see. I must be going now."

"Okay, then. Good-bye, Harry."

Suddenly, Harry began to shrink, his voice getting progressively softer. "I'm leaving now, Mum. I love you. Tell Dad I said good-bye, and that I love him, too. I'll miss you!"

Then there was a small _pop,_ and he was gone.

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At the reception, there was a table in the back corner specifically reserved for the bride, groom, and Marauders.

The five of them sat there, resting and drinking while the guests laughed and partied and had all sorts of fun.

"Funny, isn't it," began James, "how we might not have gotten together if not for our son?"

Lily nodded and smiled. "I'm glad he came to us. This is so wonderful. _You_ are so wonderful." She kissed him.

"Get a room," said Sirius, and the two love-birds broke apart, turning to smile at him.

"Ah, Sirius," said Remus, shaking his head and smiling, "when will you ever learn? You can't break these two apart. Not even before they were dating."

"Good times," said Peter, "good times."

"Not really," said James. Lily laughed.

"But still, it _is_ funny that our son brought us together."

"I'm so thankful that he did."

"Perhaps a toast is in order?" suggested Sirius.

"Good plan," said Remus. The five of them raised their glasses.

"To Harry Potter," said James, "who brought together my beloved and I so that I could sleep with her and she could give birth to him."

"Harry Potter," four other voices chorused. The five of them downed their drinks.

"You know, it's strange," Lily said suddenly, "but Harry said that he defeated Voldemort. I thought he was just kidding, but he seemed rather serious."

"Well, then, if you're going to give birth to the savior of the Wizarding World, we'd better get busy!" said James.

The other three Marauders got up and left immediately.

"Have fun," said Sirius with a wink.

And so they did.

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**Fin.**

Personally, I thought it was alright. But, of course, I wanna know what you guys think. Please leave a review!

Thanks for reading and I hope you enjoyed it.


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